I needed to add a two step login process. First the user logs in with their legacy username/password. Then, after authenticating the user the old way, I check if the use_yubikey field is true and respond with a form asking for the Yubikey OTP. That's it. Thought it was a better workflow for integrating Yubi slowly for everybody - users that don't have a yubkikey won't see the new field on the login form and the ones that get switched over will see the new form after the normal login process.
This extension to Devise adds a modified Database Authentication strategy to allow the authentication of a user with Two Factor Authentication provided by the Yubikey OTP token
This extension requires the used to already have a valid account and password and verifies that the user exists along with the password provided by verifying that the user presented a valid Yubikey OTP.
This plugin requires Rails 3.0.x, 3.1.x and 3.2.x and Devise 2.2.3+. Additionally the Yubikey Ruby library found here is required.
https://github.com/titanous/yubikey
The latest git version has a fix for a MITM attack element when communicating with the Yubico servers, this doesn't appear to be reflected in the published gem.
The gem for the Yubikey library will need to be added to your Gemfile. To install the plugin add this plugin to your Gemfile.
gem 'yubikey_database_authenticatable'
Once the plugin is installed, all you need to do is setup the user model which includes a small addition to the model itself and to the schema.
In order to communicate with the Yubikey authentication services the API key will need to be provided, this should be included into the Devise config, set yubikey_api_key and yubikey_api_id in the Devise configuration file (in config/initializers/devise.rb).
Get a key here: https://upgrade.yubico.com/getapikey/
config.yubikey_api_key = "" # => API Key must be set to validate one time passwords
config.yubikey_api_id = "" # => API ID must be set to validate one time passwords
The following needs to be added to the User module.
add_column :users, :use_yubikey, :boolean
add_column :users, :registered_yubikey, :string
then finally add to the model:
class User < ActiveRecord::Base
devise :yubikey_database_authenticatable, :trackable, :timeoutable
# Setup accessible (or protected) attributes for your model
attr_accessible :use_yubikey, :registered_yubikey, :yubiotp
attr_accessor :yubiotp
def registered_yubikey=(yubiotp)
write_attribute(:registered_yubikey, yubiotp[0..11])
end
...
end
Copyright (c) 2011-2013 Stephen Kapp, Released under MIT License
Some bits borrowed from moneytree fork of original gem.